Cosmos Era guide: how to discover all 12 civilization channels

The short answer: the 12 channels fall into three groups. One depends on a choice made on Earth (the Octopus civilization). Seven depend on events and facilities in the Interstellar civilization era (the Alpha Centauri civilization, Rama, the Black Cloud, the Tau Ceti colony, the Heptapods, the Silent probe and the Solaris Ocean). The last four depend on cosmic-scale nodes or on you giving yourself away (the Expanders, the Aestivators, the Sweepers and the Keepers). Below, each channel's location and discovery condition in turn.

Three things to remember first

• A channel is a "civilization storyline" in the game. Find one and you unlock its nodes, chapters and related endings.
• Most conditions fall in the Interstellar civilization era, so push the main line there first.
• The Sweepers are the only channel that appears because of something you did. They show up only after the main civilization has been exposed. To find the other channels safely, don't expose yourself.

The 12 channels one by one

Octopus civilization: Civilization of arms

• Location: Earth's oceans
• How to find it: unlock "Octopus civilization" in the Tree of Civilization. The prerequisite is protecting the cephalopods through all 3 mass extinctions.

Alpha Centauri civilization: Under three suns

• Location: Proxima Centauri b, 4.24 light-years
• How to find it: two routes. They find you in the Interstellar civilization era, or you go looking with "Technosignature search" or "Light sail".

Rama: Visitor

• Location: an interstellar object passing through the Solar system
• How to find it: complete "Asteroid mining" in the Interstellar civilization era and a sky survey telescope will spot it.

The Black Cloud: The thinking cloud

• Location: approaching the Sun
• How to find it: in the Interstellar civilization era, once you have a space telescope, astronomers will notice it.

Tau Ceti colony: The you that forked

• Location: Tau Ceti, 11.9 light-years
• How to find it: complete "Interstellar flight" in the Interstellar civilization era, when the first generation ship arrives at Tau Ceti.

Heptapods: Those who remember the future

• Location: Earth orbit
• How to find it: both conditions are required: unlock "Cosmic language" in the Tree of the Beyond, and build a "Mars base" in the Interstellar civilization era.

Silent probe: Bracewell's sentinel

• Location: Earth–Moon L5 point
• How to find it: both conditions are required: unlock "SETI" in the Tree of Civilization, and become a "Kardashev Type I" civilization in the Interstellar civilization era.

Expanders: A frontier coming head-on

• Location: an advancing frontier coming toward you at 80% of light speed
• How to find it: either one works: unlock "Horizon mapping" in the Tree of the Beyond, or have the main civilization complete "Galactic colonization".

Aestivators: Waiting for the universe to cool

• Location: the outer edge of the Local Group, about 4 million light-years
• How to find it: either one works: ask "Where are they?" in the Black Cloud channel, or unlock "Degenerate era" in the Tree of the Beyond.

Sweepers: Singing while working

• Location: Aquila, about 27 light-years
• How to find it: it appears only after the main civilization is exposed. Ways to be exposed: long broadcasts, firing kinetic weapons, actively sending a message, or building a Dyson sphere (waste heat can't be hidden).

Keepers: The zoo wall

• Location: inside the Solar system, unseen
• How to find it: either one works: unlock "Observer's telescope" in the Tree of the Beyond, or discover at least 5 other civilizations in the same universe (and have the main civilization already build a Dyson sphere).

Solaris Ocean: The sea that only mimics

• Location: K2-18 b, 124 light-years
• How to find it: both conditions are required: unlock "Webb telescope" in the Tree of Civilization, and build a Dyson sphere in the Interstellar civilization era.

An order by how complicated the conditions are

1. The most direct: Rama, the Black Cloud, the Tau Ceti colony. Push the main line into the Interstellar civilization era, complete the matching event or get the telescope, and they appear.
2. Needs preparation: the Octopus civilization (protect the cephalopods through 3 mass extinctions), the Heptapods, the Silent probe and the Solaris Ocean (all need a node unlocked first, then an Interstellar-era condition).
3. Needs reach: the Expanders, the Aestivators and the Keepers. Their nodes are in the Tree of the Beyond, or you must find other civilizations first.
4. Needs care: the Sweepers. They appear only after the main civilization is exposed. The ways to be exposed are listed under Sweepers above.

Location cheat sheet

• Earth's oceans: Octopus civilization.
• Earth–Moon L5 point: Silent probe.
• Earth orbit: Heptapods.
• Inside the Solar system: Keepers (unseen), the Black Cloud (approaching the Sun), Rama (passing through).
• Proxima Centauri b, 4.24 light-years: Alpha Centauri civilization.
• Tau Ceti, 11.9 light-years: Tau Ceti colony.
• Aquila, about 27 light-years: Sweepers.
• K2-18 b, 124 light-years: Solaris Ocean.
• Outer edge of the Local Group, about 4 million light-years: Aestivators.
• Advancing frontier at 80% of light speed: Expanders.

Places where players get stuck

• The Alpha Centauri civilization can be found two ways: they find you in the Interstellar civilization era, or you search with "Technosignature search" or "Light sail".
• The Aestivators can be found through the Black Cloud channel: ask "Where are they?"
• The Keepers' other condition is "discover at least 5 other civilizations in the same universe". Count how many you have found.
• The Octopus civilization requires protecting the cephalopods in all 3 mass extinctions. Check that you chose to protect them every time.

(Sources: the n, sub, where and find fields of each channel in the game data TREE.D.CHANNELS, and the related in-game ending hints.)